Monday, 24 November 2014

Critiquing a critique of Universal Darwinism

The essay Evolutionary social science and universal Darwinism argues that cultural evolution and "biological evolution" [sic] differ in various ways - and so a close parallel is inappropriate. Several of its arguments are ones that I haven't seen before. Here I will spend a moment going through them. To start with, here's a summary from the paper:

I want to propose here that there are at least four intertwined “details” about the evolution of human culture that differentiate that process from biological evolution,or at least the standard model thereof, in important ways. They are, first, the often major role of human purpose, intelligence, and intellectual interaction, both in the generation of variety, and in the selection process. Second, selection criteria and mechanisms seldom involve directly issues of human survival or reproduction. The well being of certain kinds of organizations may be at stake, but often not. Third, the entity that that is evolving — aspect of human culture — is a phenomenon that cannot simply be characterized as the aggregation of the population of traits possessed by individuals, but has a collective property. These aspects of the evolution of human culture all are involved in a fourth important difference; the way human individuals and groups are involved with culture and its evolution is different in many ways from the manner in which genes and living entities are related in the evolution of species.

In turn:

Human intelligence and purpose often provide selection on human DNA as well as on cultural variation. It is called "sexual selection" and it is standard orthodoxy in evolutionary biology.

If you argue that cultural evolution differs from biological evolution because it "seldom involves directly issues of human survival or reproduction", you should support the same claim for ant evolution, worm evolution, fish evolution - which also "seldom involves directly issues of human survival or reproduction". Yet the idea is that Darwinism applies to ant evolution, worm evolution, fish evolution and human evolution - despite their differences. Evolution need not directly involve issues of human survival or reproduction. This is widely understood.

Next, it is not true that in standard evolutionary theory, the entity that that is evolving must be a phenomenon that can be characterized as the aggregation of the population of traits possessed by individuals. An ant nest is not simply the aggregation of the population of traits possessed by individuals. A multi-cellular organism is not simply an aggregation of the population of traits possessed by individuals. Such a perspective ignores emergence, which is a standard idea in complex systems theory.

The author's presentation of their last point is a bit vague. The author expands on it later, writing:

Even in its more flexible version, it seems to me that a number of the proponents of Universal Darwinism are arguing not simply that cultural change proceeds through a process that involves variation and selection, which was Darwin’s broad proposal regarding the evolution of biological species, but also that it is useful to see cultural evolution as involving gene-like things, and phenotype-like things, with their relationships similar to those in biology. It should be obvious that I am in full accord regarding the former proposition. However, the latter part strikes me as trying to see the details of cultural evolution as like the details of biological evolution. This may not be helpful to attempts to see what really is going on, or at least not helpful regarding all areas of culture.

That's right - cultural evolution has memes - and there are meme products as well as gene products. You can quantify the proportion of the variation in an object that is due to genes and memes. For example, most of the variation in kilts is due to memes, while most of the variation in haemoglobin is due to genes.

In cultural evolution there are more "naked memes" than there are "naked genes" in the organic realm. However, this is likely to be because the organic realm is more mature. There were probably more "naked genes" in the organic realm back closer to the origin of life. It is hard to see how this counts as a real difference between the two realms.

That just leaves mutations that are directed by intelligence. That's a reasonable example of how cultural evolution actually differs from the evolution of nucleic acid and protein systems. Of course, nucleic acids are catching up these days - with genetic engineering - so the distinction is rapidly vanishing.

Of course, one can argue that the brain is not the only organ that outputs adaptive complexity within the lifetime of the host organism. The immune system does this as well - finding adaptive solutions to environmental problems without the host dying. The gut also outputs a stream of adaptive complexity in response to the diet of the host - in the form of bacteria. Seen in these contexts, the brain is not doing such a special job by solving problems.

The alleged intelligent mutations are actually themselves the product of an extended evolutionary process within the brain - involving multiple rounds of copying with selection and mindless variation. Entities copied within brains include axon spikes and ideas. Once you understand that the brain evolves, mutations that are directed by intelligence do not seem so miraculous and special: there is Darwinism all the way down.